Governments across the world are implementing legislation for ever more strict limits for vehicle emissions; combined with customer expectations for growing levels of performance and equipment, automotive manufacturers face a significant challenge. With the aim of meeting this challenge, downsizing is an established trend in passenger car engine development. However, since downsizing is commonly achieved through pressure charging (turbocharging, for example), the associated benefits in improved fuel economy and emissions are often obtained at the expense of engine dynamic response, and, consequently, vehicle driveability. This thesis presents predominantly simulation-based research into a novel combined charging system comprising a conventional turbocharger used in conjunction with a declutchable supercharger driven through a CVT. An initial investigation using this system in place of a variable geometry turbocharger on an already downsized passenger car diesel engine demonstrated greatly increased low speed torque as well as improved dynamic response. A downsizing project that involved replacing a naturally aspirated gasoline engine with a highly boosted engine with 40% of the original displacement formed the basis for more extensive investigations. Although it was unable to produce the low speed transient response of the naturally aspirated engine, in tip-in tests the CVT-supercharger system was shown to achieve the target torque much quicker than an equivalent system with a fixed supercharger drive ratio. However, balancing this with good fuel efficiency for the initial part load period was a complex trade-off. In vehicle acceleration simulations the CVT-supercharger system did not outperform the fixed drive ratio configuration, but on the CVT system the boost limit was reached at an early stage during the transients. Thus there may be potential to include an ‘over-boost’ facility, allowing boost pressure to temporarily exceed normal steady state limits in order to improve transient performance and bring it closer to that of the baseline vehicle. It is suggested that the CVT-supercharger provides the best flexibility for calibration and compromise between performance and fuel efficiency, perhaps incorporating different user-selectable modes (such as ‘economy’ and ‘sport’ modes).

In this study, application of computational fluid dynamics to ground vehicle aerodynamics was investigated. Two types of vehicle models namely, Ahmed Body and MIRA Notchback Body and their scaled models were used. A commercial software &quot / Fluent&quot / was used and the effects of implementing different turbulence models with wall functions were observed. As a result, an appropriate turbulence model was selected to use in the study. The drag forces, surface pressure distributions and wake formations were investigated in simulation of various test cases available in the literature. The study was extended to simulate the aerodynamics of the vehicles in close-following situation. The results were then compared with available wind tunnel test data.

The importance of service level management has come to the fore in recent years as computing power becomes more and more of a commodity. In order to present a consistently high quality of service systems must be rigorously analysed, even before implementation, and monitored to ensure these goals can be achieved. The tools and algorithms found in performability analysis offer a potentially ideal method to formally specify and analyse performance and reliability models. This thesis examines Markov reward models, a formalism based on continuous time Markov chains, and it's usage in the generation and analysis of service levels. The particular solution technique we employ in this thesis is model checking, using Continuous Reward Logic as a means to specify requirement and constraints on the model. We survey the current tools available allowing model checking to be performed on Markov reward models. Specifically we extended the Erlangen-Twente Markov Chain Checker to be able to solve Markov reward models by taking advantage of the Duality theorem of Continuous Stochastic Reward Logic, of which Continuous Reward Logic is a sub-logic. We are also concerned with the specification techniques available for Markov reward models, which have in the past merely been extensions to the available specification techniques for continuous time Markov chains. We implement a production rule system using Ruby, a high level language, and show the advantages gained by using it's native interpreter and language features in order to cut down on implementation time and code size. The limitations inherent in Markov reward models are discussed and we focus on the issue of zero reward states. Previous algorithms used to remove zero reward states, while preserving the numerical properties of the model, could potentially alter it's logical properties. We propose algorithms based on analysing the continuous reward logic requirement beforehand to determine whether a zero reward state can be removed safely as well as an approach based on substitution of zero reward states. We also investigate limitations on multiple reward structures and the ability to solve for both time and reward. Finally we perform a case study on a Beowulf parallel computing cluster using Markov reward models and the ETMCC tool, demonstrating their usefulness in the implementation of performability analysis and the determination of the service levels that can be offered by the cluster to it's users.

The automated functional and performance analysis of communication systems specified with some Formal Description Technique has long been the goal of telecommunication engineers. In the past SDL and Petri nets have been the most popular FDTs for the purpose. With the growth in popularity of UML the most obvious question to ask is whether one can translate one or more UML diagrams describing a system to a performance model. Until the advent of UML 2.0, that has been an impossible task since the semantics were not clear. Even though the UML semantics are still not clear for the purpose, with UML 2.0 now released and using ITU recommendation Z.109, we describe in this dissertation a methodology and tool called proSPEX (protocol Software Performance Engineering using XMI), for the design and performance analysis of communication protocols specified with UML. Our first consideration in the development of our methodology was to identify the roles of UML 2.0 diagrams in the performance modelling process. In addition, questions regarding the specification of non-functional duration contraints, or temporal aspects, were considered. We developed a semantic time model with which a lack of means of specifying communication delay and processing times in the language are addressed. Environmental characteristics such as channel bandwidth and buffer space can be specified and realistic assumptions are made regarding time and signal transfer. With proSPEX we aimed to integrate a commercial UML 2.0 model editing tool and a discrete-event simulation library. Such an approach has been advocated as being necessary in order to develop a closer integration of performance engineering with formal design and implementation methodologies. In order to realize the integration we firstly identified a suitable simulation library and then extended the library with features required to represent high-level SDL abstractions, such as extended finite state machines (EFSM) and signal addressing. In implementing proSPEX we filtered the XML output of our editor and used text templates for code generation. The filtering of the XML output and the need to extend our simulation library with EFSM abstractions was found to be significant implementation challenges. Lastly, in order to to illustrate the utility of proSPEX we conducted a performance analysis case-study in which the efficient short remote operations (ESRO) protocol is used in a wireless e-commerce scenario.

The Weighted Histogram Analysis Method (WHAM) is a technique used to calculate free energy from molecular simulation data. WHAM recombines biased distributions of samples from multiple Umbrella Sampling simulations to yield an estimate of the global unbiased distribution. The WHAM algorithm iterates two coupled, non-linear, equations, until convergence at an acceptable level of accuracy. The equations have quadratic time complexity for a single reaction coordinate. However, this increases exponentially with the number of reaction coordinates under investigation, which makes multidimensional WHAM a computationally expensive procedure. There is potential to use general purpose graphics processing units (GPGPU) to accelerate the execution of the algorithm. Here we develop and evaluate a multidimensional GPGPU WHAM implementation to investigate the potential speed-up attained over its CPU counterpart. In addition, to avoid the cost of multiple Molecular Dynamics simulations and for validation of the implementations we develop a test system to generate samples analogous to Umbrella Sampling simulations. We observe a maximum problem size dependent speed-up of approximately 19 for the GPGPU optimized WHAM implementation over our single threaded CPU optimized version. We find that the WHAM algorithm is amenable to GPU acceleration, which provides the means to study ever more complex molecular systems in reduced time periods.

The creation of 3D models for games and simulations is generally a time-consuming and labour intensive task. Forested landscapes are an important component of many large virtual environments in games and film. To create the many individual tree models required for forests requires a large numbers of artists and a great deal of time. In order to reduce modelling time procedural methods are often used. Such methods allow tree models to be created automatically and relatively quickly, albeit at potentially reduced quality. Although the process is faster than manual creation, it can still be slow and resource-intensive for large forests. The main contribution of this work is the development of an efficient procedural generation system for creating large forests. Our system uses L-Systems, a grammar based procedural technique, to generate each tree. We explore two approaches to accelerating the creation of large forests. First, we demonstrate performance improvements for the creation of individual trees in the forest, by reducing the computation required by the underlying L-Systems. Second, we reduce the memory overhead by sharing geometry between trees using a novel branch instancing approach. Test results show that our scheme significantly improves the speed of forest generation over naive methods: our system is able to generate over 100, 000 trees in approximately 2 seconds, while using a modest amount of memory. With respect to improving L-System processing, one of our methods achieves a 25% speed up over traditional methods at the cost of a small amount of additional memory, while our second method manages a 99% reduction in memory at the expense of a small amount of extra processing.

Computational tools play an important role in the description of biological systems. Scientists describe and study structure, conformational changes and interactions between molecules in silico, often as a cheaper and faster alternative for biosynthesis. The simulated dynamic behavior in time of a molecular system is a straight forward source of information about substrate-enzyme interactions at the atomic level, and a powerful tool for the identification of molecular properties important in enzymatic reactions. Our study is focused on the computational investigation of structure and substrate specificity of hydrolases important in biotransformation. The computational work was performed in close collaboration with biochemists-experimentalists from Charles University and the Microbiological Institute of the Academy of Sciences of the Czech Republic. Hydrolases have great a potential in the chemoenzymatic synthesis of modified carbohydrates with regulated properties. Carbohydrates, as substrates of hydrolases, are important in normal functionality of many organisms. They have a dual role in immune response regulation: some carbohydrates (like GlcNAc and ManNAc) participate in activation and some (like GalNAc) in suppressing immunity; glycosidase deficiency is associated with a number of lysosomal disorders. We used homology modeling, computational docking and molecular dynamics simulation (MD) methods for the complex study of fungal hydrolases: alpha-galactosidase/alpha-N-acetylgalactosaminidase from Aspergillus niger; beta-N-acetylhexosaminidases (HEX) (from Aspergillus oryzae and Penicillium oxalicum); nitrilase from Aspergillus niger. Our structural study unambigously demonstrates that the enzyme encoded by genes variant A (aglA) from A. niger is able to accept alpha-N-acetylgalactosamine as its substrate and explains structural features responsible for its specificity. Homology models of HEXs from P. oxalicum and A. oryzae were built and compared. Homology models were used to study the role of protein glycosylation, disulfide bonds, dimer formation and interaction with natural and modified substrates. Model of nitrilase from Aspergillus niger helped to analyze multimer formation.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In recent years, several studies have been conducted in order to investigate the problems related to reduced quality of water for public supply, recreation, irrigation, among others, leading to the identification of pollution sources and to develop proposals for its control. Improper use of water has caused serious problems especially in urban centers. The increasing contamination of water resources, caused by several sources, among which stand out the domestic sewage, industrial effluent and urban and agricultural diffuse load, is compromising the use of these resources for their various purposes. The Poxim River is an important source of Sergipe, which supplies a large number of farms and part of the capital Aracaju. Within this context, to understand and try to minimize the problem in a rational manner, we can tell, nowadays, with monitoring of water quality in watersheds and the development and application of tools that consider aspects of quantity and quality. The aim of this study was to monitor and analyze water quality through physical-chemical and microbiological contaminants in the sub-basin of Rio Poxim of different aspects of use and occupation and the possible interference that may cause these water resources, Besides using a computational tool AcquaNet able to simulate critical processes and scenarios for sub-basin, considering the framing parameters of water bodies, in accordance with Resolution 357/2005. To guarantee the water supplyment in amount and quality for agroecosystems and ecosystems associates to the river depends on the planning and management of the water resources that must be thought adopting the hydrographic basins as basic units of planning. / Nos últimos anos vários estudos têm sido realizados com o intuito de investigar os problemas relacionados com a redução da qualidade da água para o abastecimento público, lazer, irrigação, entre outros, levando a identificação das fontes poluidoras, bem como a elaboração de propostas para o seu controle. O uso inadequado da água tem gerado sérios problemas principalmente nos centros urbanos. A crescente contaminação dos recursos hídricos, causada por diversas fontes, dentre as quais destacam-se os efluentes domésticos; os efluentes industriais e a carga difusa urbana e agrícola, vem comprometendo o uso destes recursos para os seus diversos fins. O Rio Poxim é um importante manancial do estado de Sergipe, que abastece um grande número de propriedades rurais e parte da capital Aracaju. Dentro desse contexto, para compreender e tentar minimizar o problema de maneira racional pode-se contar, atualmente, com o monitoramento da qualidade da água em bacias hidrográficas e o desenvolvimento e aplicação de ferramentas que consideram aspectos de quantidade e qualidade. O objetivo deste estudo foi monitorar e analisar a qualidade da água através de parâmetros físico-químicos e microbiológico na sub-bacia hidrográfica do Rio Poxim quanto a diferentes aspectos de uso e ocupação do solo e as possíveis interferências que estes pode provocar nos recursos hídricos, além de usar uma ferramenta computacional AcquaNet capaz de simular processos e cenários críticos para a sub-bacia, considerando os parâmetros de enquadramento dos corpos d água, de acordo com a resolução CONAMA 357/2005. Garantir o suprimento de água em quantidade e qualidade para os agroecossistemas e ecossistemas associados ao rio depende do planejamento e gestão dos recursos hídricos que devem ser pensados, adotando-se as bacias hidrográficas como unidades básicas de planejamento.

The aim of this paper is to acquaint the readers with basic classification of wind turbine configuration by used electric generator, with speed and power control used in power plants and with mathematical model of wind and parts of power plant. Procedure of making model in applications Mathematica and MathModelica is described in the other part of this paper. There were made models of power plants with squirrel cage asynchronous generator, one with pitch control, the other with stall control. In the last part of the thesis comparison of model behavior of both models with the same input conditions was made.

Organische Schadstoffe werden in vielen Phasen unseres täglichen Lebens in den Wasserkreislauf eingeleitet. Die herkömmliche Abwasserbehandlung ist nicht zur effektiven Entfernung einiger dieser Stoffe, insbesondere von Arzneimitteln, geeignet. Die Fotokatalyse basierend auf der Suspension von katalytischen Nanopartikeln und ultraviolettem Licht stellt eine effiziente Methode dar, um diese organischen Stoffe im Abwasser zu reduzieren. Während das allgemeine Konzept der fotokatalytischen Wasserreinigung gut etabliert ist, fehlte ein beschreibendes und einfach anwendbares Modell der wesentlichen Abbauprozesse. Ein solches Modell ist entscheidend, um experimentelle Ergebnisse systematisch vergleichen zu können, und stellt eine wertvolle Hilfe bei der Optimierung von Prozessen dar. Diese Arbeit präsentiert einen Modellierungsansatz zur Simulation der kinetischen Prozesse basierend auf dem Langmuir-Hinshelwood-Mechanismus. Dieses Grundmodell wurde erweitert, um auch die Bildung von organischen Zwischenprodukten zu beschreiben. Diese Erweiterungen basieren entweder auf einem inkrementellen oder einen fragmentierenden Abbaumechanismus, der durch das Einbinden von überschüssigen Bindungen ergänzt werden kann. Die simulierte Konzentrationsentwicklung von Zwischenprodukten sowie die Entwicklung des verbleibenden organischen Kohlenstoffes werden für verschiedene Modellannahmen bezüglich ihrer Desorptionsraten von der Photokatalysatoroberfläche diskutiert. Die Modellparameter wurden aus dem Vergleich mit experimentellen Ergebnissen ermittelt. Grundlegende Experimente wurden unter Verwendung des Antibiotikums Ciprofloxacin und des Farbstoffs Methylenblau als Beispiele für organische Verbindungen und Titandioxid und Zinkoxid als fotokatalytische Materialien durchgeführt. Darüber hinaus wird die Anwendbarkeit des Modells auf komplexere Systeme durch den Vergleich mit dem fotokatalytischen Abbau von 14 Medikamenten im Abfluss von Kläranlagen demonstriert. Nach der Evaluierung des Modells wurde es in ein Open-Source-Softwarepaket implementiert, um eine breitere Anwendung zu ermöglichen und eine solide Grundlage für weitergehende Entwicklungen zu schaffen.:Abstract Kurzfassung Symbols Constants Abbreviations 1. Motivation 2. Introduction 2.1. Modeling and simulation 2.2. Heterogeneous photocatalysis 2.2.1. History 2.2.2. Semiconductor band structure 2.2.3. Interface between a semiconductor and a redox electrolyte 2.3. Photocatalytic material 2.3.1. Overview 2.3.2. Titanium dioxide 2.3.3. Zinc oxide 2.4. Light sources 2.4.1. Solar 2.4.2. Fluorescent tubes and mercury-vapor lamps 2.4.3. Light-emitting diodes 2.4.4. Organic light-emitting diodes 3. Materials and methods 3.1. Analytic methods 3.1.1. Nanoparticle characterization 3.1.2. Ultraviolet-visible absorption spectrometry 3.1.3. SPE-HPLC-MS/MS 3.1.4. Non-purgeable organic carbon 3.2. Experimental investigations 3.2.1. Model substances 3.2.2. Adsorption-desorption 3.2.3. Photocatalytic degradation 3.2.4. Wastewater treatment plant effluent 3.3. Modeling approach 3.3.1. Single organic species model 3.3.2. Multiple organic species model 3.4. Model implementation 3.4.1. Development objectives 3.4.2. Molecule parameters 3.4.3. Solving the differential equation system 3.4.4. Fit to experimental results 3.4.5. Availability 4. Results and discussion 4.1. Nanoparticle properties 4.2. Adsorption-desorption 4.3. Photocatalytic degradation 4.3.1. Single organic species model 4.3.2. Multi organic species model 4.4. Wastewater treatment plant effluent 4.4.1. Influence of effluent 4.4.2. Degradation of pharmaceuticals in the effluent 5. Conclusions Appendix A. Analytical solution B. Effluent pharmaceuticals concentrations C. pdom handbook List of figures List of tables Bibliography / Organic pollutants are discharged into the water cycle at many stages in our daily lives. Conventional wastewater treatments are ineffective in the removal of some of them, especially clearing pharmaceuticals. Photocatalytic degradation utilizing catalytic nanosuspensions under ultraviolet irradiation represents an efficient method to reduce those organic components in the wastewater. While the general concept of photocatalytic water purification is well established, a descriptive and easy to use model of the essential processes was missing. Such a model is critical to ensure the systematic comparability of experimental results and supports process optimization. This work presents a modeling approach to simulate the involved kinetic processes based on the Langmuir–Hinshelwood mechanism. Further, the fundamental model is extended to include the formation of intermediate organic components. This extension uses either an incremental degradation mechanism or a fragmentation based mechanism, that can include excess bonds. The simulated concentration evolution of intermediates, as well as the evolution of the total organic carbon, are discussed for different model assumptions concerning their desorption rates from the photocatalyst surface. The model parameters were estimated from comparison with experimental findings. Basic experiments were performed using the antibiotic ciprofloxacin, and the dye methylene blue as organic compounds and titanium dioxid and zinc oxide as photocatalytic materials. Furthermore, the application of the model to more complex systems is shown by the photocatalytic degradation of 14 pharmaceuticals in wastewater treatment plant effluent. Following successful evaluation of this model, it was implemented in an open-source software package to enable a wider adoption and a sound foundation for further developments.:Abstract Kurzfassung Symbols Constants Abbreviations 1. Motivation 2. Introduction 2.1. Modeling and simulation 2.2. Heterogeneous photocatalysis 2.2.1. History 2.2.2. Semiconductor band structure 2.2.3. Interface between a semiconductor and a redox electrolyte 2.3. Photocatalytic material 2.3.1. Overview 2.3.2. Titanium dioxide 2.3.3. Zinc oxide 2.4. Light sources 2.4.1. Solar 2.4.2. Fluorescent tubes and mercury-vapor lamps 2.4.3. Light-emitting diodes 2.4.4. Organic light-emitting diodes 3. Materials and methods 3.1. Analytic methods 3.1.1. Nanoparticle characterization 3.1.2. Ultraviolet-visible absorption spectrometry 3.1.3. SPE-HPLC-MS/MS 3.1.4. Non-purgeable organic carbon 3.2. Experimental investigations 3.2.1. Model substances 3.2.2. Adsorption-desorption 3.2.3. Photocatalytic degradation 3.2.4. Wastewater treatment plant effluent 3.3. Modeling approach 3.3.1. Single organic species model 3.3.2. Multiple organic species model 3.4. Model implementation 3.4.1. Development objectives 3.4.2. Molecule parameters 3.4.3. Solving the differential equation system 3.4.4. Fit to experimental results 3.4.5. Availability 4. Results and discussion 4.1. Nanoparticle properties 4.2. Adsorption-desorption 4.3. Photocatalytic degradation 4.3.1. Single organic species model 4.3.2. Multi organic species model 4.4. Wastewater treatment plant effluent 4.4.1. Influence of effluent 4.4.2. Degradation of pharmaceuticals in the effluent 5. Conclusions Appendix A. Analytical solution B. Effluent pharmaceuticals concentrations C. pdom handbook List of figures List of tables Bibliography